Drive systems are well known in a wide variety of diverse applications. They oftentimes utilize mechanical transmissions that are highly effective for the intended purpose but which, nevertheless, could prove dangerous particularly during maintenance procedures. Specifically, the mechanical transmission could cause serious injury if inadvertently engaged at such times.
One particular application which is illustrative of this problem involves an aircraft cargo door. Such doors utilize mechanical actuation systems driven by power drive units that require a ground check-out by skilled personnel. If others are unaware of the presence of such skilled personnel, the actuation system could inadvertently be operated at an instant that would cause serious injury.
To overcome such problems, manual lockouts have been proposed in various forms. For instance, Lindemeyer U.S. Pat. No. 4,464,948 is directed to a locking mechanism for an indexing device which utilizes an eccentric cam fixed from axial movement but rotatably mounted on a spindle whereby camming surfaces inclined toward one another engage opposing surfaces of adjacent gear teeth of the drive system. Unfortunately, the Lindemeyer '948 patent is unsatisfactory because it will not engage regardless of the relative position of the gear teeth and the eccentric cam.
Similarly, Schoepe U.S. Pat. No. 3,618,427 discloses a mechanism for locking a turret of a machine tool. This is accomplished by interference of teeth on a rack with gear teeth. Once again, however, the Shoepe '427 patent only allows locking to occur at discreet positions.
Still other locking mechanisms are disclosed in Forquerus U.S. Pat. No. 4,503,899 and Malkowski et al U.S. Pat. No. 4,441,379. Nevertheless, it has remained to provide a mechanical transmission locking device that will engage every time without regard to position. In other words, earlier attempts to provide lockouts have failed to accomplish the objective of positive locking at an infinite number of positions. More specifically, it has remained to provide a locking mechanism which is automatically self-aligning regardless of position. On the contrary, manual lockouts have required discreet relative positioning for locking engagement.
The present invention is directed to overcoming the above stated problems and accomplishing the stated objects.